This chapter gives an overview of the internal structure of
the backend of PostgreSQL. After
having read the following sections you should have an idea of how
a query is processed. This chapter does not aim to provide a
detailed description of the internal operation of PostgreSQL, as such a document would be very
extensive. Rather, this chapter is intended to help the reader
understand the general sequence of operations that occur within
the backend from the point at which a query is received, to the
point at which the results are returned to the client.